Eliza Taylor, Henry Ian Cusick, Marie Avgeropoulos, Lindsey Morgan, Christopher Larkin and Richard Harmon were all on hand to rehash the previous season’s conflicts, as well as give a glimpse of what’s ahead. Here’s what we learned:

* The audience was treated to an ominous shot of a cloud of smoke and lightning approaching Polis, which executive producer Jason Rothenberg explained is a hint about what’s to come, though that “probably wouldn’t be until the end of the season. … The earth strikes back in Season 4. … It’s an unbeatable foe. It becomes not how to stop it; it becomes, ‘How do we survive?’ There aren’t enough life boats. … It’s a return in a lot of ways, thematically, to what we did in Season 1. … The earth is the Ark.”

* “It’s going to be interesting to watch a group of people, humans, trying to survive,” Taylor added. “This is an enemy we can’t defeat, so how do we move forward? In true Clarke fashion, that will be trying to get everyone on board.”

* Kane’s biggest Season 4 struggle, Cusick explained, will be to hold everyone together without falling apart, himself: “Kane is fairly pragmatic, even though he’s grown a lot. One of the things I like about him is that he sees what needs to be done. Hopefully he won’t delve too much into the PTSD. As a good leader, I’d hope he’d put others before him.”

* Octavia is headed for a “really dark turn,” Avgeropoulos said. “Yes, it’s possible to go darker. … She’s going to go ahead and do what she does best, which is killing people.”

* Morgan referred to her character as Raven 2.0, following her ALIE upgrade: “She went through an evolution, almost a reincarnation.”

* Roan and Indra, whose statuses were up in the air at the end of Season 3, will both return for Season 4. In fact, Zach McGowan (Roan) has been promoted to series regular.

* Luna will also return in Season 4, “She was a breath of fresh air,” Rothenberg said. “I don’t want to spoil how she enters the scene, but it’s a world that’s beginning to collapse, environmentally. What ALIE mentioned — black rain, boils, all the plagues of the Bible start coming down.”

* Season 3 was originally supposed to end with Jasper emerging from the City of Light… and “blowing his brains out,” Rothenberg revealed. “It was too dark, even for me. I don’t think anyone will ever see that scene. It was a horrible way to leave what was a really dark season.”

* Though Lexa won’t be returning in Season 4, Rothenberg assured fans that the Flame will remain an important political artifact.